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Biomedical subjects

R MacKenzie

Publications and source records attributed to R MacKenzie.

At least 55 records · Page 3Linked to original sources
PubMed1992

Adolescent health care in a large multispecialty prepaid group practice. Who provides it and how well are they doing?

Adolescents are at risk for pregnancy, sexually transmitted diseases, suicide, homicide, accidents, and substance abuse. Adolescent medicine involves an overlap of many skills needed to provide routine medical care, as well as care for those conditions that require psychosocial assessment. We report the results of a mail survey covering care of this age group by practitioners of pediatrics, internal medicine, obstetrics and gynecology, family practice, and adolescent medicine in a large, multispecialty, prepaid group practice. The mail survey covered 10 areas of adolescent care. Adolescent medicine physicians expressed the highest level of perceived knowledge and competence in these areas, with family practitioners ranked second. More than 50% of internists and pediatricians felt only fair to poor competence for a variety of adolescent conditions, whereas a third of internists and pediatricians reported that they liked to care for adolescents. Physicians in all 4 of the primary care specialties reported a need for a teen health center for both consultation and education. These results are similar to those reported for pediatricians and primary care physicians in private practice and for residents in internal medicine.

Adolescent Medicine↗
PubMed1991

A68930: a potent agonist selective for the dopamine D1 receptor.

A68930, (1R,3S)-1-aminomethyl-5,6-dihydroxy-3-phenylisochroman HCl, is a potent (EC50 = 2.5 nM), partial (intrinsic activity = 66% of dopamine) agonist in the fish retina dopamine-sensitive adenylate cyclase model of the D1 dopamine receptor. In the rat caudate-putamen model of the D1 dopamine receptor, A68930 is a potent (EC50 = 2.1 nM) full agonist. In contrast, A68930 is a much weaker (EC50 = 3920 nM) full agonist in a biochemical model of the dopamine D2 receptor. The orientation of the 3-phenyl substituent in the molecule is critical for the affinity and selectivity of the molecule towards the dopamine D1 receptor. A68930 also displays weak alpha 2-agonist activity but the molecule is virtually inactive at the alpha 1- and beta-adrenoceptors. When tested in rats bearing a unilateral 6-OHDA lesion of the nigro-neostriatal neurons, A68930 elicits prolonged (greater than 20 h) contralateral turning that is antagonized by dopamine D1 receptor selective doses of SCH 23390 but not by D2 receptor selective doses of haloperidol. In this lesioned rat model, A68930 increases 2-deoxyglucose accumulation in the lesioned substantia nigra, pars reticulata. When tested in normal rats, A68930 elicits hyperactivity and, at higher doses, produces a forelimb clonus.

Adenylyl Cyclases↗
PubMed1991

Synthesis and dopaminergic activity of 3-substituted 1-(aminomethyl)-3,4-dihydro-5,6-dihydroxy-1H-2-benzopyrans: characterization of an auxiliary binding region in the D1 receptor.

The synthesis and dopaminergic activity of a series of C3 and nitrogen-substituted 1-(aminomethyl)-3,4-dihydro-5,6-dihydroxy-1H-2-benzopyrans (isochromans) is described. The synthesis of the compounds was stereospecific for the 1,3 cis isomer, and the enantioselective synthesis of both enantiomers of one of the analogues (20) was achieved. It was determined that all of the dopaminergic activity resides in the [1R,3S] isomer. Generally, substitution at the C3 position provided compounds with very high potency (less than 10 nm EC50) and selectivity for the D1 receptor, with a wide range of intrinsic activities (60-160%). Analogues containing C3 substituents including aryl, arylalkyl, and cyclic and acyclic alkyl groups showed a marked enhancement of dopaminergic activity compared to the unsubstituted compound. As a class, the drugs were orally active in the rat rotation model with a very long duration of action.

Adenylyl Cyclases↗
PubMed1991

Synthesis and pharmacological evaluation of 1-(aminomethyl)-3,4-dihydro-5-hydroxy-1H-2-benzopyrans as dopamine D1 selective ligands.

A series of 3-substituted 1-(aminomethyl)-3,4-dihydro-5-hydroxy-1H-2- benzopyrans were prepared as potential D1 selective antagonists. The compounds were evaluated for their affinity and selectivity for the D1 receptor as well as for their functional antagonism of D1-mediated pharmacological events. The compounds show potent D1 antagonist properties in vitro. The optimum nitrogen substitution was found to be the primary amine and the observed order of potency for substitution at the 6-position is OH greater than Br greater than H greater than OMe. Two representative compounds, the 6-methyl and 6-bromo analogues, were also evaluated in vivo for dopaminergic activity. Interestingly, both compounds behave as potent in vivo agonists.

Adenylyl Cyclase Inhibitors↗
PubMed1990

Orthopaedic manifestations of blastomycosis.

The cases of seventy-two patients who had blastomycosis and were seen between 1926 and 1988 were retrospectively reviewed for involvement of the musculoskeletal system. Most patients were from rural rather than urban areas (almost a 2:1 ratio), and an especially large number were from northwestern Ontario or were native Indians (primarily Ojibwa). Bone was the second most common site of involvement (seventeen patients); in approximately one-half of these patients, the osseous site did not cause symptoms. Metaphyses of long bones and small bones were involved the most; the metaphyseal lesions tended to be eccentric, well circumscribed, and lytic. There were two deaths--the most recent, more than twenty years ago--of patients who had involvement of bones and joints; these patients, by modern standards, had had inadequate treatment. Treatment with amphotericin B and, more recently, with ketoconazole, in conjunction with operative treatment, was very effective.

Amphotericin B↗
PubMed1988

A risk profile comparison of runaway and non-runaway youth.

All initial visits (N = 765) to an outpatient medical clinic during calendar year 1985 were analyzed. Six hundred and fifty-five of these visits made by non-runaway youth were compared to 110 visits made by runaways. Based on data from the Childrens Hospital Adolescent Risk Profile Interview, runaway street youth are at greater risk for a wide variety of medical problems and of health-compromising behaviors including suicide and depression, prostitution, and drug use. The implications for public health and social policy are discussed.

Adolescent↗
PubMed1988

Continuous narcotic infusion with patient-controlled analgesia for chronic cancer pain in outpatients.

STUDY OBJECTIVE: To determine the feasibility and safety of outpatient continuous narcotic infusions with additional bolus capabilities (patient-controlled analgesia) in patients with cancer pain. DESIGN: A single arm (non-randomized) series. SETTING: Outpatient with contact by telephone and through outpatient clinic. PATIENTS: Consecutive series of 18 patients with poorly controlled cancer pain or significant side effects from regular administration of various narcotics. INTERVENTIONS: Patients taught and supervised to use portable pump capable of delivering a continuous narcotic infusion with bolus capabilities. MEASUREMENTS AND MAIN RESULTS: All patients had improvement in pain control as judged by the use of a linear analogue scale. Side effects and safety profile were highly acceptable. Narcotics used and maximum doses were meperidine, 50 mg/h; morphine, 80 mg/hr; and hydromorphone, 60 mg/hr. Infusion duration ranged from 7 to 225 days (mean, 54 days). CONCLUSIONS: Continuous narcotic infusions using a programmable portable pump with bolus capabilities is a safe and reliable method of delivering narcotics to outpatients.

Adult↗
PubMed1987

Perioperative myocardial infarction with coronary artery surgery: diagnosis, incidence and consequences.

Perioperative myocardial infarction is a potential consequence of coronary artery bypass surgery. The diagnosis is difficult due to multiple factors including postoperative chest discomfort, serum enzyme elevations and nonspecific electrocardiographic changes. No one test is reliable, but a combination of electrocardiogram, MBCK serum enzyme analysis and technetium pyrophosphate scanning should increase the probability of correct diagnosis. Using this method, the incidence of perioperative myocardial infarction in this study was six out of 100. Left ventricular function in the early postoperative period was adversely affected by perioperative myocardial infarction with a reduction in left ventricular ejection fraction (63 +/- 9% preoperative to 54 +/- 12% postoperative; P less than 0.05), whereas left ventricular ejection fraction was unchanged in the absence of perioperative myocardial infarction. The long term left ventricular function, however, appears to recover, and at two years after surgery there was no difference in rest or exercise left ventricular function between patients who suffered perioperative myocardial infarction versus those who did not. All patients with perioperative myocardial infarction survived to be discharged from hospital, and all returned for follow-up at two years. Their functional and work status was no different from those without perioperative myocardial infarction. This would suggest that, if patients survive a perioperative myocardial infarction, their long term functional status is no different from those patients without perioperative myocardial infarction.

Adult↗
PubMed1986

Conservative management of the injured spleen in children.

Five children under 11 years of age with traumatic rupture of the spleen were treated conservatively (non-operatively) and showed recovery of the injured spleen after an initial period of instability. The progress was monitored clinically, ultrasonically and with radionuclide scans.

Bacterial Infections↗
PubMed1985

Early-stage Hodgkin's disease: current approaches to treatment.

Most patients with early-stage Hodgkin's disease can now be cured by one of several therapeutic approaches. This review highlights the developments in the diagnosis and treatment of the disease that have led to long-term survival rates greater than 90%. Past and present radio-therapy (RT) planning and treatment practices are discussed in the context of both clinical and pathological staging. The role of initial bimodal therapy (RT and chemotherapy [CT]) and the use of CT in patients who suffer relapse after initial treatment with RT alone are reviewed. On the basis of prognostic factors, subgroups of patients for whom bimodal therapy is recommended, including those with a bulky mediastinal mass, have now been identified. Although treatment is highly successful, debilitating consequences of RT and CT, such as infertility, infection and second malignant diseases, remain. Newer treatment regimens may reduce morbidity and have similar or better long-term results with respect to survival and quality of life.

Acute Disease↗
PubMed1985

Evidence against a role for superoxide ions in the injury of nephrotoxic nephritis in rats.

The accelerated model of nephrotoxic serum nephritis (NTSN) was produced in 12 Sprague-Dawley rats. Six of these rats were administered superoxide dismutase (EC 1.15.1.1; SOD) subcutaneously (8 mg/kg) 8-hourly for 4 days. The first dose was given 6 h before the nephrotoxic serum (NTS). The progression of renal disease was monitored by following (i) albumin excretion, (ii) serum creatinine and creatinine clearance and (iii) renal histopathology and immunofluorescence. There was no evidence that SOD influences the course of NTSN. SOD was scarcely excreted by control rats or rats with NTSN.

Albuminuria↗
PubMed1982

Localization in transcortical sensory aphasia.

Transcortical sensory aphasia is a syndrome characterized by poor comprehension but excellent repetition. The lesions shown on computed tomography and isotope scans of 15 patients who satisfied the objective criteria based on test scores were studied. The overlap technique showed a unique posterior parieto-occipital location of lesions. The lesions seem to separate into two groups: one is more medial, inferior, and posterior and is clearly in the posterior cerebral artery territory, and the other is relatively more lateral, superior, and anterior and seems to be in a watershed area between middle cerebral and posterior cerebral arteries. The lesion sizes correlated with severity. Frequent recovery and good prognosis are associated with this entity. Association with transient visual agnosia and hemianopsia confirmed the anatomical correlation.

Aged↗